[PATCH] D146637: [InstCombine] Try to recognize bswap pattern when calling fshl

[Jun Zhang via Phabricator via llvm-commits]

junaire updated this revision to Diff 507606.
junaire added a comment.

Put the transform in the right place.


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D146637/new/

https://reviews.llvm.org/D146637

Files:
  llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
  llvm/test/Transforms/InstCombine/bswap.ll


Index: llvm/test/Transforms/InstCombine/bswap.ll
===================================================================
--- llvm/test/Transforms/InstCombine/bswap.ll
+++ llvm/test/Transforms/InstCombine/bswap.ll
@@ -932,17 +932,7 @@
 
 define i64 @PR60690_call_fshl(i64 %result) {
 ; CHECK-LABEL: @PR60690_call_fshl(
-; CHECK-NEXT:    [[AND_I:%.*]] = lshr i64 [[RESULT:%.*]], 8
-; CHECK-NEXT:    [[SHR_I:%.*]] = and i64 [[AND_I]], 71777214294589695
-; CHECK-NEXT:    [[AND1_I:%.*]] = shl i64 [[RESULT]], 8
-; CHECK-NEXT:    [[SHL_I:%.*]] = and i64 [[AND1_I]], -71777214294589696
-; CHECK-NEXT:    [[OR_I:%.*]] = or i64 [[SHR_I]], [[SHL_I]]
-; CHECK-NEXT:    [[AND_I7:%.*]] = shl i64 [[OR_I]], 16
-; CHECK-NEXT:    [[SHL_I8:%.*]] = and i64 [[AND_I7]], -281470681808896
-; CHECK-NEXT:    [[AND1_I9:%.*]] = lshr i64 [[OR_I]], 16
-; CHECK-NEXT:    [[SHR_I10:%.*]] = and i64 [[AND1_I9]], 281470681808895
-; CHECK-NEXT:    [[OR_I11:%.*]] = or i64 [[SHL_I8]], [[SHR_I10]]
-; CHECK-NEXT:    [[OR_I12:%.*]] = tail call i64 @llvm.fshl.i64(i64 [[OR_I11]], i64 [[OR_I11]], i64 32)
+; CHECK-NEXT:    [[OR_I12:%.*]] = call i64 @llvm.bswap.i64(i64 [[RESULT:%.*]])
 ; CHECK-NEXT:    ret i64 [[OR_I12]]
 ;
   %and.i = lshr i64 %result, 8
@@ -962,17 +952,7 @@
 
 define i64 @PR60690_call_fshr(i64 %result) {
 ; CHECK-LABEL: @PR60690_call_fshr(
-; CHECK-NEXT:    [[AND_I:%.*]] = lshr i64 [[RESULT:%.*]], 8
-; CHECK-NEXT:    [[SHR_I:%.*]] = and i64 [[AND_I]], 71777214294589695
-; CHECK-NEXT:    [[AND1_I:%.*]] = shl i64 [[RESULT]], 8
-; CHECK-NEXT:    [[SHL_I:%.*]] = and i64 [[AND1_I]], -71777214294589696
-; CHECK-NEXT:    [[OR_I:%.*]] = or i64 [[SHR_I]], [[SHL_I]]
-; CHECK-NEXT:    [[AND_I7:%.*]] = shl i64 [[OR_I]], 16
-; CHECK-NEXT:    [[SHL_I8:%.*]] = and i64 [[AND_I7]], -281470681808896
-; CHECK-NEXT:    [[AND1_I9:%.*]] = lshr i64 [[OR_I]], 16
-; CHECK-NEXT:    [[SHR_I10:%.*]] = and i64 [[AND1_I9]], 281470681808895
-; CHECK-NEXT:    [[OR_I11:%.*]] = or i64 [[SHL_I8]], [[SHR_I10]]
-; CHECK-NEXT:    [[OR_I12:%.*]] = call i64 @llvm.fshl.i64(i64 [[OR_I11]], i64 [[OR_I11]], i64 32)
+; CHECK-NEXT:    [[OR_I12:%.*]] = call i64 @llvm.bswap.i64(i64 [[RESULT:%.*]])
 ; CHECK-NEXT:    ret i64 [[OR_I12]]
 ;
   %and.i = lshr i64 %result, 8
Index: llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
===================================================================
--- llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
+++ llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
@@ -1783,6 +1783,10 @@
         return BinaryOperator::CreateLShr(Op1,
                                           ConstantExpr::getSub(WidthC, ShAmtC));
 
+      if (Instruction *BitOp =
+              matchBSwapOrBitReverse(*II, /*MatchBSwaps*/ true,
+                                     /*MatchBitReversals*/ true))
+        return BitOp;
       // fshl i16 X, X, 8 --> bswap i16 X (reduce to more-specific form)
       if (Op0 == Op1 && BitWidth == 16 && match(ShAmtC, m_SpecificInt(8))) {
         Module *Mod = II->getModule();


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